Neutrino mass and lepton-asymmetry in Scotogenic model

Abstract

In this literature we show how the scotogenic frame work can be a common origin for explaining neutrino mass, lepton asymmetry and give a dark matter candidate. We start out with the extension of the Standard Model with fermions, which are odd under a discrete symmetry, with the SM-like fermions we also have a doublet scalar field like Higgs but odd under discrete symmetry. This model has potential similar to the inert doublet model, which implies we can have a Dark Matter candidate similar to IDM, the Dark matter aspect and calculation of DM parameters are not discussed extensively. In this model, we can calculate the mass of neutrinos from loop corrections that were massless at the tree level, and define a physical mass matrix which requires the inclusion of the Weinberg operator. Then we look at lepton number violation through decays of heavy Majorana neutrinos, these generate a lepton asymmetry, then with the help of sphalerons they convert the excess of lepton number to baryon number, this conversion is quantified by conversion factor. To calculate the number densities we use the Boltzmann equation, and CP asymmetry parameter which gives us the net lepton number produced, at last, the present baryon-to-photon ratio is estimated.